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Re: Frenguellisaurus ischigualastensis
On Fri, 15 Jan 1999, Christopher Srnka wrote:
> DinosØMP wrote:
> > 1)
> > With "Allosaurus, Megalosaurus, Giganotosaurus etc.", do you want
> > to say
> > "Tetanurids"?
> Yes, but I was thinking of those three in particular. My only reference for
> the appearance
> of the skeleton was the Dinosaur Encyclopedia, and I thought the drawing of
> the skull
> reminded me more of Allosaurus and Giganotosaurus (both of which I have seen
> mounts of) than Herrerasaurus. I was just wondering.
As well it should! *Megalosaurus* is considerably higher up in the
theropod tree than *Herrerasaurus* is. That said, *M* does not show a
particularly close affinity with *Allosaurus* and *Giganotosaurus*.
*Allo* is in the Allosauridae, along with *Neovenator* and a number of
questionable genera: *Saurophaganax*, *Wyomingraptor*, *Epanterias*,
*Giganotosaurus* is in the Carcharodontosauridae with
*Carcharodontosaurus* and *Acrocanthosaurus* (and apparently something new
The Allosauridae and Carcharodontosauridae, along with the Sinraptoridae
(*Sinraptor*, *Yangchuanosaurus*, ?*"Szechuanosaurus"*, ?*Siamotyrannus*),
form the Allosauroidea.
The Allosauroidea and a handful of other animals (?*Afrovenator*,
?*Cryolophosaurus*, possibly spinosaurs--their ischia show features found
elsewhere only in Allosauroidea, *Afrovenator*, *Marshosaurus*, and
*Gasosaurus*) form the Carnosauria ("all organisms more closely related to
*Allosaurus* than to birds").
The Carnosauria and the Coelurosauria (compsognathids, *Ornitholestes*,
*Deltadromeus*, *Bagaraatan*, *Tyrannosaurus*, *Deinonychus*,
*Segnosaurus*, *Rahonavis*, *Gallus*, *Corvus*, etc., etc.) together form
the Avetheropoda (or Neotetanurae).
It is at this point that *Megalosaurus*, *Torvosaurus*, *Monolophosaurus*,
and others join the tree--these, along with the Avetheropoda, form the
Tetanurae ("all organisms more closely related to birds than to
So, to answer your question, no, *Megalosaurus*, *Allosaurus*, and
*Giganotosaurus* do not form a natural group, as far as we can tell.
Pacific Lutheran University
Tacoma, WA 98447